Method of and means for cooling substances such as liquids in bulk



Dec. 19, 1961 G. BROOKER ETAI.

SUCH AS LIQUIDS IN BULK Filed Jan. 22, 1957 w/mrazwome E. G. J. A. 7 J. R.

E. METHOD OF AND MEANS FOR COOLING SUBSTANCES 2 Sheets-Sheet 1 INVENTORS BROOKER KINGSTON K N 0X ATTORNEYS Dec. 19, 1961 E. G. BROOKER EI'AL 3,013,402

METHOD OF AND MEANS FOR COOLING SUBSTANCES SUCH AS LIQUIDS IN BULK Filed Jan. 22, 1957 2 Sheets-Sheet 2 INVENTORS E. G. BROOKER J. A. KINGSTON J. R. KNOX By WM/ ATTORNE Ys 7% J A/X L I United States Patent Ofiice 3,013,402 Patented Dec. 19, 1961 METHOD OF AND MEANS FOR COOLING SUB- STANCES SUCH AS LIQUIDS IN BULK Eric Gordon Brooker, Jonas Arthur Kingston, and

Joseph R. Knox, Reading, England, assignors to Gascoignes (Reading) Limited, Reading, England, a British company Filed Jan. 22, 1957, Ser. No. 635,378 1 Claim. (Cl. 62-171) This invention is concerned with the bulk cooling of liquids, particularly milk.

It is an object of the invention to provide bulk cooling apparatus utilizing a method of adjusting the temperature of a cooling medium by localized freezing thereof from a plurality of freezing lines so that a substantially continuous ice wall is formed, the volume of cooling medium employed and the form of the ice wall chamber containing said cooling medium being such that the ice wall is submerged in cold but unfrozen cooling medium.

Another object of the invention is to provide bulk cooling apparatus in which the ice wall chamber is in the form of a space enclosed between double walls, the bulk liquid to be cooled being flanked by ice wall chambers on several sides, encompassed all round or entirely surrounded by double-shell ice wall chambers.

The presence of some cold but unfrozen cooling medium around the ice wall serves for the transmission of heat from the bulk liquid to the ice wall, which cools the bulk liquid and tends to melt the ice wall. The latter is, however, maintained in the frozen or congealed state by heat extraction by feeding a refrigerant to the freezing points or lines. The free cooling medium around the ice wall may be agitated by forcing thereinto jets of a gaseous medium, such as air.

A further object therefore is to provide bulk cooling apparatus for carrying the above described method of bulk cooling into eifect in which means are provided for agitating the cooling medium, usually plain water, during an ice-wall forming period.

Bulk liquid cooling tanks have been proposed having a horizontal refrigeration coil on the bottom and being surrounded by a liquid cooling medium, a cooling medium spray being used for cooling the sides of the bulk tank. One advantage of a bulk cooling tank according to this invention is that an evaporator coil (or coils) go round the vertical sides of the tank and so result in the formation of a vertical ice wall. A further advantage is that the cooling water employed may fill a vertical space extending to near the top of the tank, so that the bulk liquid being cooled is surrounded on all four sides and preferably at the bottom also with a cooling medium.

Another advantage, when air is used for agitating the cooling water in order to get rapid ice melting, is that this air agitation may be and preferably is applied to both sides of the ice wall, thereby ensuring equal distribution of the agitating air over the whole surface of the ice wall and thus providing the maximum rate of ice melting.

After the liquid in the tank has been reduced to the required temperature (say 40 F. in the case of milk) it will not rise above this temperature, because the water jacket surrounding the tank will be at a lower temperature. Any heat absorption into the cooled liquid will be transmitted into the water jacket and will cause ice to melt, in this way preventing a rise in temperature.

If water is being cooled in a non-jacketed bulk tank then, since the point of maximum density of water is approximately 39 F., below this point the coldest water rises to the top and the warmest water goes to the bottom. This means that for water cooling thermostatic control can be placed in the bottom of the bulk tank.

We have found, however, that if milk is being cooled in the bulk tank, it behaves in the opposite way of water,

the point of maximum density of milk being lower than 39 F. This means that for commercial cooling, the coldest milk remains at the bottom of the tank and the warmest milk rises to the top, with the result that thermostatic control cannot be placed near the bottom of the bulk tank. However the thermostatic control instrument cannot be placed in bulk liquid tank itself, near the top thereof, because sometimes milk in a partially filled tank has to be cooled. By providing an outer jacket which can be filled to the top, as in the apparatus hereinafter described, this difficulty is overcome, because to a great degree stratification of milk in the bulk tank is avoided and the thermostatic control can be placed near the bottom.

An example of a bulk cooling apparatus primarily intended for milk is illustrated in the accompanying drawings, wherein:

' FIGURE 1 is a vertical sectional elevation through one form of bulk milk cooler;

FIGURE 2 is a sectional plan on line II-I-I of FIG- UR'E l; and

FIG. 3 is a schematic representation of the connections between the agitator motor, air pump motor and the liquid thermostat.

The apparatus illustrated in the drawings comprises an open-top rectangular or square tank 5 of double-wall construction, with heat insulating lagging 2 packed between the double walls of the tank and an inner tank I mounted within outer tank 5. The spaces 3 between the side walls 4 and 4A of the four. opposing sides of the outer tank 5 and inner tank 1 are in open communication and within said communicating spaces an evaporator coil 6 is supported by pillars 7 out of contact with the side walls 4, 4A, the evaporator coil 6 being suitably connected to an electric motor driven refrigeration compressor (not shown).

The vertical distance x between adjacent convolutions or circuits of the evaporator coil 6 is such that when the required quantity of ice is formed on the coil convolutions a solid vertical bank of ice 8 is obtained extending approximately over the full depth of the space 3. This bank of ice 8 is thus formed all around the vertical outer surface of the side wall 4A of the inner tank 1. The tank could, of course, be circular, but whatever the shape in plan it is preferable that the side walls are vertical.

It is known that the rate of heat transfer from water to a refrigerant decreases rapidly as the thickness of the ice around an evaporator coil increases, so that a point is reached when the rate of formation of ice drops to a low level. The spacing y between the outer and the inner walls 4, 4A of the outer and inner tanks is of a dimension sufiicient to obviate the possibility of all the water 9 in the space 3 being turned into ice. There is, therefore, always free water on both sides of the ice bank '8, and as already mentioned this free water in the space 3, after the ice bank 8 is fully formed, is used as a means for the transmission. of heat from the milk in the tank to the ice, resulting in the melting of the latter.

If desired, and as shown, the bottom 10 of the outer tank 1 is also of double wall construction and provided with lagging 10A.

As a means of agitating the free water 9 in the space 3, air is discharged through holes 13 in a distribution pipe 14 (or pipes) placed adjacent to the bottom of the ice bank 8. This air is supplied by an air pump (not shown), through pipe 14A, and it is important that no lubrication be used in this pump because of the danger of oil getting into the cooling water and coating the heat transmission surfaces. In order to render the tank bottom more effective for heat exchange purposes pipes 15 to emit jets of air may be installed underneath the floor 11 of the inner tank, so that it will fiow in space 12 between the two floors and emerge in the space 3 adjacent the ice bank 8. Air for agitation purposes may be drawn from just above the surface of the free water 9 in the space 3, thus ensuring that cold air, and not higher temperature ambient air, is used for agitation.

The thickness of the ice bank 8 is controlled by a thermostat 27 connected to the suction side of the refrigeration coil and is operated by the temperature of the refrigeration gas. This thermostatic control is connected to the refrigeration compressor.

The temperature of the liquid in the tank is thermostatically controlled by a thermostat 28 immersed in the liquid, said thermostat being coupled with the controls of said air pump and with a milk agitator motor herein after referred to. A diagrammatic circuit of this coupling is shown in FIG. 3.

To ensure adequate drainage the floor 11 of the inner tank 1 may be inclined relatively to the horizontal and provided with a sump 11a separated from the floor 11A of outer tank only by a rubber joint ring or pad 16. A tubular seating 17, for a delivery bung 18, extends through the sump 11a, the outer tank floor 11A and the interposed pad 16 to connect with an outlet pipe 19, the bung 18 being operable by a handle 18a accessible through a door 20 in the tank cover 21. The inner walls 4A and the floor 11 of the inner tank may be stififened as shown by welding channel strips 22 thereto. When the space 3 is filled with water and the inner tank 1 is empty the forces of buoyancy will exert an upward force on said inner tank and to hold it in position holdingdown bolts 23 extend down through fioor 11A and bottom 18 and is secured at 23A. These bolts 23 act also as feet when the inner tank 1 is full of milk. The outer tank 5 is carried on adjustable legs 24.

To assist in the cooling of the milk in the inner tank 1, a power driven agitator is provided in the form of a mixer blade 25 driven by an electric motor 26.

As a precautionary measure, for use in the event of breakdown of the refrigerating plant, suitable means may be provided for removing some heat from a liquid which is in the tank for cooling. This may be done by connecting the space 3 with a source of water, such as an existing water main. Incoming water would be delivered to the bottom of the space 3 by a down pipe, and an overflow pipe would be provided at or near the top of said space.

We claim:

A bulk milk cooler comprising a heat insulated tank, an inner milk receiving tank fixed in said heat insulated tank and spaced from the walls of said heat insulated tank, evaporator tubing vertically positioned between the walls of said heat insulated tank and said inner tank and spaced from the walls of said inner tank, an outlet in the bottom of said inner tank extending through the bottom of said heat insulated tank, and coolant agitating means between the walls of said heat insulated tank and said inner tank and positioned directly beneath said vertically positioned evaporator tubing for agitating a coolant, a milk agitator means mounted Within said inner tank and a thermostat means within said inner tank and coupled with said milk agitator means and with said coolant agitating means, whereby when a coolant is placed in the space between the walls of said heat in sulated tank and said inner tank and a refrigerant is run through said evaporator tubing, the coolant will form an ice bank on said tubing and said coolant agitating means will agitate the coolant and limit the formation of the ice bank so that all of the coolant will not turn to ice, and the milk in the inner tank will be cooled, and when the temperature of the milk being cooled rises above a predetermined temperature, said thermostat means starts said milk agitator means and said coolant agitating means to reduce the milk temperature.

References Cited in the file of this patent UNITED STATES PATENTS 1,046,252 Berryman Dec. 3, 1912 2,139,576 Davis Dec. 6, 1938 2,380,901 Chamberlain July 31, 1945 2,494,512 Kafer et al. Jan. 10, 1950 2,674,101 Calling Apr. 6, 1954 2,785,545 Pusey Mar. 19, 1957 

